c++中const变量真的不可以修改吗？

转载于 2016-03-15 10:03:32 发布 · 7.7k 阅读

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本文通过两个示例展示了如何使用const_cast去除常量限定，并探讨了由此带来的潜在问题。第一个示例成功修改了常量整数的值，而第二个示例则因在全局作用域尝试相同操作而导致段错误。

代码一：

<span style="font-size:18px;">#include <iostream>
using namespace std;

int main()
{
    const int a = 3;
    int* p = const_cast<int*>(&a);
    *p = 4;
    cout << "value of p: " << *p << endl;
    cout << "value of a: " << a << endl;
    cout << "address of p: " << p << endl;
    cout << "address of a: " << &a << endl;

    return 0;
}      </span><span style="font-size: 24px;">    </span>

运行结果

value of p: 4
value of a: 3
address of p: 0x22fe34
address of a: 0x22fe34

--------------------------------
Process exited after 0.9921 seconds with return value 0
请按任意键继续. . .

代码二：

#include <iostream>
using namespace std;
const int a = 3;
int main()
{
	//const int a = 3;
   	int* p = const_cast<int*>(&a);
   	*p = 4;
   	cout << "value of p: " << *p << endl;
   	cout << "value of a: " << a << endl;
  	cout << "address of p: " << p << endl;
  	cout << "address of a: " << &a << endl;

  return 0;
}

运行结果:

Segmentation fault (core dumped)